Secondary Storage

Disk Caching

Disk cache may refer to:
-Disk buffer, the small amount of buffer memory present on a hard drive.
-Page cache, the cache of disk pages kept by the operating systems, stored in unused main memory.
-General application-level caching of data stored on the disk.
-Readyboost, a non-volatile disk cache stored on flash memory device,in Windows Vista and Windows 7.

File Compression

- allows users to make one or more files into a smaller zip file.
-is  the process of encoding information using fewer bits than the original representation would use.
-helps reduce the consumption of expensive resources, such as hard disk space or transmission bandwidth.

File Decompression

-reduces the size of a file by minimizing redundant data.

- redundant data can be frequently occuring characters, such as the space character, or common vowels, such as the letters e and a.

-Data compression creates a compressed version of a file by minimizing this redundant data.

Internet hard Disk

- a magneticdisk on which you can store computer data.
- Hard is used to distinguish it from a soft, floppy, disk.
-consists of several platters, one platter needs two read/write heads, one for each side.
-attacted to a single access arm for not moving indepently.
-Has the same numeber of tracks, and a track location that cuts across all platters is called a cylinder.

Optical Disk Drive

- a disk drive that uses laser light or electromagnetic waves near the light spectrum as part of the process of reading or writing data to or from optical discs.

- an integral part of stand-alone consumer appliances such CD players, DVD players and DVD recorders.

- some can oly read from discs, but recent drives are both generally readers and recorders.

-these recorders can be called or known as burners or writers.



Solid State Storage

- a data storage device that uses solid-state memory to store persistent data with the intention of providing access in the sane manner of a manner of traditional block i/o hard disk drive.
-known as SSD ( solid state drive)
-devices contain spinning disks and moveable read/write heads.
-use microchips which retain data in non-volatile memory chips and contain no moving parts.